https://forums.augi.com/showthread ... lect-polyline-segment
Public Sub SelectNestedPolyline()
Dim doc As Document = Application.DocumentManager.MdiActiveDocument
Dim db As Database = doc.Database
Dim ed As Editor = doc.Editor
' Prompt the user to select a polyline segment.
Dim options As New PromptNestedEntityOptions(vbLf & "Select a polyline segment: ")
options.AllowNone = False
Dim result As PromptNestedEntityResult = ed.GetNestedEntity(options)
If result.Status <> PromptStatus.OK Then
Return
End If
' If the selected entity is a polyline.
If result.ObjectId.ObjectClass.Name = "AcDbPolyline" Then
' Start a transaction to open the selected polyline.
Using tr As Transaction = db.TransactionManager.StartTransaction()
' Transform the picked point from current UCS to WCS.
Dim wcsPickedPoint As Point3d = result.PickedPoint.TransformBy(ed.CurrentUserCoordinateSystem)
' Open the polyline.
Dim pline As Polyline = DirectCast(tr.GetObject(result.ObjectId, OpenMode.ForRead), Polyline)
' Get the closest point to picked point on the polyline.
' If the polyline is nested, it's needed to transform the picked point using the
' the transformation matrix that is applied to the polyline by its containers.
Dim pointOnPline As Point3d = _
If(result.GetContainers().Length = 0, _
pline.GetClosestPointTo(wcsPickedPoint, False), _
pline.GetClosestPointTo(wcsPickedPoint.TransformBy(result.Transform.Inverse()), False))
' Get the selected segment index.
Dim segmentIndex As Integer = CInt(pline.GetParameterAtPoint(pointOnPline))
ed.WriteMessage(vbLf & "Selected segment index: {0}", segmentIndex)
tr.Commit()
End Using
End If
End Sub
